The present invention relates to respiratory circuits and particularly to tracheostomy tubes comprising of an outer constant radius cannula and a removable inner cannula.
Tracheostomy tubes with removable inner cannula are well known in the prior art. When a two part tracheostomy tube is placed in the patients trachea, if the patients tracheostomy should become occluded by mucus or phlegm, the tracheostomy tube airway can be cleaned by removing the inner cannula. After being cleaned, the inner cannula can be placed inside the outer cannula of the tracheostomy tube which remains in place in the trachea.
Various means of connecting the inner cannula to the tracheostomy tube and connecting the tracheostomy tube to a ventilation system and the like are also well known. Examples showing various connecting means are: U.S. Pat. No. 3,088,466 to Nichols; U.S. Pat. No. 3,659,612 to Shiley, et al.; U.S. Pat. No. 4,009,720 to Crandall, et al.; and U.S. Pat. No. 4,315,545 to Crandall, et al., also assigned to Shiley. All of these patents show various means for interconnecting the inner cannula and the outer tracheostomy tube cannula by means of a coupling connector. It is common for all of these patents, that the coupling connecting means to the ventilator or the like is integral with or connected to the removable inner cannula and that an additional connection is required between the outer tracheostomy tube cannula and the body of the inner cannula.
Tracheostomy tubes of this design have several disadvantages. First, they require an additional disconnection point between the outer and inner cannula which reduces the safety of the system. Such prior art tracheostomy tube devices must have an air tight seal between the inner and outer cannulae and at the ventilator connecting means which is typically part of the inner cannula.
Second, the need exists in the art to improve the security of the respiratory system so that the accidental disconnection of the parts of the tracheostomy tube assembly can be prevented. At the present time there is no interconnecting system in the respiratory art that can provide high security for the connection of an inner cannula within a respiratory circuit.
Third, the need has been emphasized for some time to provide a system which will only be disconnectable at the ventilator connecting means. The problem is discussed in a study by Arthur D. Little entitled: "Accidental Disconnection of Breathing Circuits". The current state of the art tracheostomy devices, by design and preferred embodiment, require an additonal disconnection point which reduces the safety of the patient. The preferred embodiment of the present invention, proposes to overcome the above discussed disadvantages of the prior art.
According to the preferred embodiment of the present invention, the ventilator circuit is provided with a tracheostomy tube having a ventilator connection means integral to the outer tracheostomy tube cannula, and a removable inner cannula tube made separately from the outer cannula and placeable inside the outer cannula and the ventilator connection means. This design enhances the safety of the respiratory air delivery system. The removable inner cannula is safely placed inside the connector while the device is attached to various ventilator connection means such as elbows, swivels, connectors, etc. minimizing the possibility of unintentional disconnection.